SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbcc334137d2a592803fb197f6bbbbcf8936d5a8e126c7ece5a06710d7f9e708' 
  AND token = 'x8SsbmMdRecR4Y4zQAKk8dMxNpIhwKQ98MBN4TuMcTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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