SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c990c00f121129b259382c109bb2c7a8222d11c0e352b46d8f18ba293b73a20' 
  AND token = 'hU888VJDm42APLsF2UGpLJVvVSTGmNX8kLaqSFSiDkM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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