SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b96ab79da7f271206c720827cb49be3f9ec292f8f08d9ecdbea87d4b12ae2655' 
  AND token = '3vGsMhmwSYEji+GzkDXSNJMKnfrh00FyB3Byqh1sR/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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