SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f9df8d76b047480970f37981b17af51ec49c603b2d79c8cd35a2ca59c85b2ce4' 
  AND token = 'f7ahuLul56T8SDPdEzLqHCOrN6V7rSihVIBIc49CGII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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