SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '735fc7843d9a8fe82c225b3a050f19d994bda0989a2e48f710e6360758a0f820' 
  AND token = 'D5bpewYfHPY53dhdLx0xWZVNpw+3BVFyBxn1BCXXUrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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