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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98a4e7b9acbe317f49b1ca937542dffe85f1d2b3df54bf2e228781fe808eada1' 
  AND token = '55cPY+oag/WOR28qVofTxjs+RqESQo6sQKiCmCFdeHc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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