SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3e88f7569c9a7d014ca8b6c352fc6b1b80b36245b081fad5baa84cada130adc' 
  AND token = '324/OXDB+MsBk9Fo/XzORjWx9jBLJ1HrhZ6qkK/NxB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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