SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70994ba50fce1246b3756fa749d3677533981401d3c3be6d494568dc9d65b21d' 
  AND token = '7v/QaSXV1wfVxmjvEmYge/VHuwr419ljlfuaH43zqvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00077

JSON explain

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