SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad99ed156e48a6a37bb46700b47a81b6e79799a0b8bdad7fc948ab1e12a13c21' 
  AND token = 'mZJNU9YjOZG3Ya/y7CHlqgvZAreeKqHQqX7oDM5+JIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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