SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4a9628d5cc7ad8283f3d52cbc0de86a739d4f8f4045403117f73dc894753916' 
  AND token = 'TKlPFbo1zq21hSwtTFOVx9Z5yFkQ+U2YvOOb51kh/Jc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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