SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3096832968a15ef2f02ab358886cb1d8774374fc1a10a2737bafb5034d98c71' 
  AND token = 'VRoMjrGqHiPZvdhG+IerAs+uut3wgOs8Qsy9V7mYCxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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