SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bf887c3ededd73cc2bfa8468c1015320693aa387fd3cdaadd6014fad31ebac9e' 
  AND token = 'Z9A2bZ2B+0Ix2Ti9JduEzLbjnYs+pcukv6ufq02HtPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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