SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b7b021e4e72894d9f42b809664a5c87c4050234f5290905bdce9f9a8a3a27e7' 
  AND token = 'gtgszAQ7zC3SmoBbRAdouzGRDtRGnYmboCJJTXUorRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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