SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c261adc81f392e5933023bd6eb7cb786764c0e5a37b51cad56bb7d4d92a09245' 
  AND token = '0HzeYoJOVBmq3DDKrGj20KaSFbW+XyKv1uBXQNr4Lck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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