SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a73bb2164863b1d0f0c4125441250782170eaa357cc3a40b8a8ae4f107de7a4' 
  AND token = 'JNDAaw42Xv57j2Ia278aKQhKsvGLdwxDIMlZlOgxSTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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