SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73f088cda015d6594f7bb032cb3a9524acd00e68d4dde8d6078195ae14fea0e3' 
  AND token = 'sQi54F3qJhTpSUkPug8Gfa1EUccOuygfZEzf+eAmH0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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