SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68dab52e523eccff3b095e2d747a3a21b49525b76856cf75b1878e7027341b20' 
  AND token = 'ys3J+6mcx87zCCPp+qsDMx9nDFtLRsdFHLROUhUFo9A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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