SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50191707c281d7ebbcc0384a066ff7b7781f67f8935504e25f2a7e9550078b32' 
  AND token = 'Lv5mfRC5qKKbxLHlV0kqdv7LOEJF5+/8OqVLkqCApgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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