SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c100fb99167830a09363cc3969865575f26b8f4fc2ed4d2fd6feb337f2b8ff8' 
  AND token = 'iS/cRpDbYtBMbYKNL3rRQKxZngQ6d3oa+sfl1nizghc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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