SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f73ef90e435c4e828768a0d82fb6cd7f0afe041ecb72b170359f5ca5430fdf21' 
  AND token = 'qtrZrDjhB+1eyM1R+3xjBzRiIRyc5sgrluC+gDFLGrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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