SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '24ef788ae4b6ed29266b08695ff013b36359f57baa92b9055bfaec793474622f' 
  AND token = '+wmgOJe1ffUmQYgLutjeaDIpBcDIQCyKOfr9Z1Bxlmc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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