SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb553618dfa50d9795b4f00346c6d3a87237b5e9380ad5d5697f382e102a8549' 
  AND token = 'GDN5CM1/AYjV1qOYSRQMzPMSuALjMmBcPimCHSRU0FQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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