SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3031b6b27489f94a82ae0ae3ead71d5510af988892ac137ae337b36a6065509c' 
  AND token = '2SKHow1RynBjzz+FGj/H3KPiZxxsKp2aHYpzdUzkA/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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