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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bcc9c070faaf679134539642ac4ea1db83c1edd09f2afaa7efaa708d84167fb6' 
  AND token = 'nWnu7Fv88vvcE7uQzUQ6bJ7P9GZFNvtMVTKK79d+arQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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