SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '868cda490ac975657677c589208dfef0945c1335c0fb1e0878d363dd1cc4e692' 
  AND token = 'jUAzGZhTP7mTmWiQLEqDkAx2RDJ6vdbNW+mv9AqhRqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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