SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc785c73383e582a238ac4c52b2d765ab6d9bb325ddd668f733356f4f9da78eb' 
  AND token = 'VmH7xf6AymaUU4sXKHXgytpOuo+frmRnqUmr2DDbpm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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