SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c266cf1c9d1a484647b2507bd0d8178c378c28ef4020790d9768994cf31af4f5' 
  AND token = 'pl5UK2VeUIU+y/jkqS02fosGQlYTG3i26CZMhrihRNE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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