SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8506d450f0a303096887781400d97f7b88fbb025e2bb613cec13f4ae4db95a4' 
  AND token = '/jFJKCANaMa9VCYbYuvJoY7dlD2Tqcxzgxl2B13xf/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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