SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50a4baf5ba53228302fbf34d63da28672d95b933acf35ecc3b3fbbb0dd1ae6be' 
  AND token = 'tzeIliQulPe8r55HzqIw2tRcOPLVYbp1C9ByPQgKRjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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