SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b44cb56d6622da6a742bed973fa2bfad2ef7be976054e22140aa930c698bc44' 
  AND token = 'uLcBD6xZvG7OtWScJC0z2CCtEvID+1zzDzXXm3jg8LE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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