SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b944595068312f966833bf20ccf09bbbc2be05852d2650008a2616c75334a0d9' 
  AND token = 'S07pCQ+5PGKqnZwg5RIaxqD/erokhCNx1f3E2rpSBrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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