SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '844fbee84a54892b6e6d4ab86daba11024140ba70f8acd6c43fd778604c61403' 
  AND token = 'gRFqy8ui4pwTBGmvmFLYYEZdis84a+dszuschkVzlVw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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