SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0fff7dab32ef0837883d25793faf819c9e908091dec2d0ffddd986644c20557' 
  AND token = 'nQW0W8vE/vStmhTjYKUGss5zbZfQqtX7ZSZwb0+jgsE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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