SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4578fb1055d1b520e1901774b35c333236b882aea2ad3ed40856a2ba75112f67' 
  AND token = 'MVcOQHK364dx+c5gmRgW1b7w6AxYxbxPilrGFtP+Tn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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