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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3b6be2b453041531678af2bbcc51d55e03ffe2f77a67f660c1fb9e8c12ebfe5' 
  AND token = 'blz0jnTjjeoQNsRwU9MEkAF3+l/TJ/CdCIE+lCE44Sk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00065

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}