SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a33157878acdf047387f4ff3251c3d7403843856cc723dd107c6029a0de823d' 
  AND token = 'VeXinyUbaLrCzEJ9rBjGoU5wyI86tht+KS4EnZK+YQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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