SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a9649639c020d84f5eb23c61f0f91b9b998ccf952753b8416c4d2828e3f1373' 
  AND token = 'akcx0oAPRBJEfsqPiLFlWCmgZp1psGfUmtajRriIH50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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