SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f382818bda54fc74e7a6d84291818cc92bd34858ba09b3b409745c987f616aec' 
  AND token = 'B6T274l8y7bqqWhjcJrw4pTIGs+XoKf7lb4q8uExtBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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