SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '189da644c557b7bba06d22bb75d220e0d9a83b5855064cf7f111a570d7fc7083' 
  AND token = '7cpTjfyYEsNkM3g0Ghb36YEgYf8YVTJsHihV0jAUFV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00079

JSON explain

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