SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '451e77cf78f400406a6ac6bd2c4c0ecc157969911d893b67f13ccbcb5caf7a13' 
  AND token = 'ozTOoiN02Ud4gOTPE3ziknmP2YW2eRPbWW2kwEeVUrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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