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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5ca6dcc84e8a529013e7790a46a11dd357b1b1777436d51553c5d1cf36fdd78d' 
  AND token = '36X9ggitc9vKmXjA60U2F2kecGeh9+oid24PJWHIH1Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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