SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6792e5a851ca7026e0de989cea784e743642d742aad52a222f00fffea792d6c' 
  AND token = 'yuIdxB61Ko8/RscoeBwFvyULS8cJchks4XNRW94P+44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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