SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c43d5bd75a88eb423e31dab2c9b556c0905cea3105d08419b7da9952ea4f04' 
  AND token = 'y5zlfXFhISX8MIAbf7+AbxJnQaSdFzK93nKyFYIWJVk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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