SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c86a52db0475c9d1ee4528154a583215e3ad60dd3953787b0185f060375a3853' 
  AND token = 'BH77jboWB/wzFRNNIvpdwRWLqWvsl9HdRZ+XAi9npN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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