SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3be747d9167d189a141d7ef1762786af9572b2f6f4244de6e7f2b869c0de6f58' 
  AND token = 'n2+wmVQvUClV8nLyvV86PFaCRGNLKewpIhSJUDXHJlk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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