SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8f759d7d31a7c74a6a1a6d7f91fd66de1d72ba7f92fbe7a75883d43eca179cc' 
  AND token = 'LH6fkoUs4uXmyvE+VAD/fgPOmyHBwg/QpoIFUQtCOrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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