SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27a265fb192e8ea860a94148307859909cd693634e6fc4620975f1f5f51edc98' 
  AND token = 'Th1JdXEX0Gdnfhyimh+ACdWMwezuTUP3x7gXjLcxVTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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