SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e214bb54cc0f87c8849753957f61582850429b7379265f6870e5b8feb86624c3' 
  AND token = 'i6KrYSL3+IRGLF45xhbJET4GccHQSA9MOoVTaqMixMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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