SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2ba59ba44b2babc1e28be6be5611dc98f6b371dfdf85318e81fc1a0988cb3c8' 
  AND token = 'qaAGADIUqGZQsvZ1pl2glsRby3JMyKMq1GlWwjmsZ0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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