SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b507a468ad1d7126163287e8f2a21719161ce32d138e12d5c3293cf966f276a' 
  AND token = '/brzVGJxXMtlb8NLSU7dvNS+ZAe3SCj3OpcUiiX6VjE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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