SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b999087ecaef509bcea9775da69c20206b0e2fe71a62d67bc2849ea8d41eca5' 
  AND token = 'xsuv7Rhaz1MNnqsWHHkJW6R51tNtMwCBotOW25+Pb8c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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