SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47d3449633fdbb70211632ef7b4dea8b0ece6e68593b491c42aca35271c1d068' 
  AND token = 'g2OCIeBZEAiVznK/KxQR1UqQwg8jwlU+27CXrMTKov0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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