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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '35ffa68c0c1b5514af6356ac57ecd767f86f4604c91491ec34812ed3d43bda3b' 
  AND token = 'Ut4Ktv3pa93sQ/3DOXVvaJ0rH7xbJDCZaT6ZIKwVvoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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