SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ccb7b2ffe4c8373006e838dd202be84620c3effbc1ed0704eab662d9621308a1' 
  AND token = 'DscVKW/zsSBRPsWEhZ7t7q2lTsEfzXHSUpgStbNGYGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}