SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f5b0ec0a1eb9b596be8e56536aac4df61f9807abda603322fd85eb22f3b88cb' 
  AND token = '831/BzXktCaREu6hX3ot0RQjwkc2FM4ra8NLVGHfg6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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