SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b12e5ba19b64c74e22234007cf009e716e1854b0af0a568841bfbcddf26ce54' 
  AND token = '/sGNEPFeJPuoNmnBMA7pHNX3dUdzIFCHTr+iaQpHvGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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