SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '206dc15112a4bb97fac1c0084175029aecc75213aeb7709709ddceea50fbeae2' 
  AND token = 'mvf45s8ZtpvKY/ugEL2jMlbEHpa29nPmUxNy8GWMnuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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