SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92aa8a4b820b6351a4cdea71691be2c2b07fa6d5aad1f5b8e642a5e3a06d81aa' 
  AND token = '8OT4rsx8cR17tuOteQ7Lmydyjfn2e8lKWxEPU7O29Hw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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