SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c80aeee59ef7e687a756757f9809063b7c9326034a45704f27726306996790c' 
  AND token = 'ajQWrOPiEnJhQhQvKnQUJ252Vzv+9YNqSi1ss5wsFj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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