SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a90bdce94165ffdc9fa14397273673b1cbcf5ea2cba0292e70bc1959c4969011' 
  AND token = 'P/KtwOFmtXiUabdz6SuRPqR0FUZ235zoA7YCHfVSSm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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