SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71b3584791155c4acfa5204c8fc4ea6f735c5fc355d8bc5ae5ce999832cb695d' 
  AND token = 'i5YNZ3nO4LYlPCPdjsgguJoHEJBMyNQGAvEo+8nYEDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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