SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b62757d506db428a6bb427ffc7a0fbee64fb16552da4cfd22166de5c2012b488' 
  AND token = 'D8nDTavwv9nh6FmjbAZ8LDdaVE40U+vBEWl+MPFs81E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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