SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4beb01ee43d22cc229f110ea4c54ab6c6d03664f3727e84153add305312be49' 
  AND token = 'x+F8EtPLGov59xe+znbNPCYWk/JUDpMtCmJypOhY7Zs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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