SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68113a0c99dac8e82671bbdaec3b42967c3b06c60182e32d51b12d06464cb058' 
  AND token = 'I/eMgnWkRf+6IQL8/rv/yG6neOvyLfYa01a4YgzdS5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}