SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8e7b0d743913f28d0cb29347331f5aef82f168445c80fc11977b0f8b4496791' 
  AND token = '2kNd+AQlrM3lF/4w1FQmVbKKCHwp9PyZRRK/XU+8D2Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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