SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f2bd93a1daee18e2d8548ed5da000b5abc9293266290641b5848671f2ca4b46' 
  AND token = 'pvcTAnVb7bNNcsDUgiQlYsS8czUWSDeMihBSWuZMwqY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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