SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '645672465be6658b7c43fb6fad60ac6820eda6e622f9d7522de1d466c83cc71a' 
  AND token = 'RpO7YmiZCOx2Zn9beh4AzmzwUVRd0tD70EizM5G4L5k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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