SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '781dff0936c8f97307e806d2561d6c60bcfd86fe2e923b0af3b8fb748f4b0282' 
  AND token = 'gPLGYFVY5IPCHVguhQ5n3ZfGJG2FwnlGODSVh7oNWOQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00064

JSON explain

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