SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3294d671f6daa51493dac7989cfe6643350dff0a9ab04974e5198b0ccad86475' 
  AND token = 'FcZlH4FC3V2tiomRCqdvBGQD7TX9dAyZQSU2hgo/bUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00067

JSON explain

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