SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c15ce05639b8316cbf4a59f83aade036e014855570784cb26cd00a3845099fae' 
  AND token = 'XJNSoa3zbClNdWoimYOq8lKGT5ZMzmanMNDFbyDRBqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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