SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c322aaaceb9fe5a5d2b636d683d85c80c88fea654e2c9dd506ad7fb9c12c3c51' 
  AND token = 'FQI326oZFsNBfWFI3TuncVaMd9n5d7rBtvztTS8NEOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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